It's time to replace another manifold stud…
Previously when installing a new MMI manifold (about a year ago), the middle stud wouldn't tighten down. So, my mechanic drilled-out the block for a helicoil which worked great to hold the manifold in place.
Now, to address a leaking exhaust flange and manifold gasket I've pulled it all apart, built a new hot section with MMI exhaust flange, and reassembled only to find the front stud not tightening (and a small water leak from the middle stud). So, time to replace the front stud.
I've read a lot on here about the different methods of replacement, have helicoils and the MMI 7/16" replacement stud, and I'll be drilling out the block on Saturday. My question is, which way is best? Once you go down one route you cannot change (even though the 7/16" tap drill bit is smaller that the helicoil drill bit - 23/32" versus 25/32" - once the 7/16" threads are cut into the block you probably aren't going to get enough bite later to install the helicoils as a subsequent repair job). Are the helicoils more likely to allow water to pass? Are they more solid and durable since you aren't relying on my ability to properly tap the hole and the integrity of the block material just beyond where it has already failed (threads)? Is the JB weld necessary for the MMI repair stud?
Thanks in advance for your sage advice!
Previously when installing a new MMI manifold (about a year ago), the middle stud wouldn't tighten down. So, my mechanic drilled-out the block for a helicoil which worked great to hold the manifold in place.
Now, to address a leaking exhaust flange and manifold gasket I've pulled it all apart, built a new hot section with MMI exhaust flange, and reassembled only to find the front stud not tightening (and a small water leak from the middle stud). So, time to replace the front stud.
I've read a lot on here about the different methods of replacement, have helicoils and the MMI 7/16" replacement stud, and I'll be drilling out the block on Saturday. My question is, which way is best? Once you go down one route you cannot change (even though the 7/16" tap drill bit is smaller that the helicoil drill bit - 23/32" versus 25/32" - once the 7/16" threads are cut into the block you probably aren't going to get enough bite later to install the helicoils as a subsequent repair job). Are the helicoils more likely to allow water to pass? Are they more solid and durable since you aren't relying on my ability to properly tap the hole and the integrity of the block material just beyond where it has already failed (threads)? Is the JB weld necessary for the MMI repair stud?
Thanks in advance for your sage advice!
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